Well Water Testing: What to Test and How Often

Private well testing explained: what to test first, how often, bacteria vs chemicals, and why a well is not automatically safer than city water.

Direct answer

If you use a private well, you are responsible for testing. At minimum, test regularly for bacteria (total coliform / E. coli) and, depending on your area, nitrate and locally common chemicals such as arsenic. A well is not automatically cleaner than treated municipal water — it is simply unregulated at the tap unless you test.

Why well water is different

City supplies are treated and monitored as a system. A household well draws groundwater that can change after floods, nearby farming, septic issues, or a cracked casing. Taste and clarity are poor substitutes for a lab test.

A practical first panel

Total coliform and E. coli
Nitrate (especially with infants in the home or intensive agriculture nearby)
pH and basic minerals / hardness
Local priorities: arsenic, fluoride, iron, manganese, or other mapped risks

Use a certified drinking-water lab. Follow their sampling instructions — a dirty tap or the wrong bottle can ruin a bacteria test.

How often

Many public-health agencies suggest at least annual bacteria testing, with extra tests after flooding, repairs, a change in taste/odour, or gastrointestinal illness in the household. Chemical tests may be less frequent unless your geology or land use suggests a risk.

After you get results

Match treatment to the finding: disinfection for confirmed bacteria (plus fixing the wellhead), and appropriate filters or other systems only for contaminants they are certified to reduce. Related: well water testing procedure, reading a water report, safe storage.

Educational overview. Local standards, lab methods, and reports differ. Use official reports and qualified local advice for decisions about your supply. About Water Omnis · Privacy.